Significantly reduced lattice thermal conductivity and enhanced thermoelectric performance of In2O3(ZnO)3 ceramics by Ga2O3 doping

The In 2 O 3 (ZnO) 3 + x mol%Ga 2 O 3 ( x  = 0, 0.1, 0.3, 0.5, 1) ceramics were synthesized by a solid-state reaction process. The effect of Ga doping on the thermoelectric properties of the In 2 O 3 (ZnO) 3 ceramics was studied. The phase structure and microstructure of all the bulk samples were checked by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM), respectively. Additionally, the minimum thermal conductivity of 1.45 Wm −1 K −1  at 973 K is obtained for 0.5% Ga-doped sample, which is 35% lower than that of the pristine sample. The significantly decreased thermal conductivity for Ga 2 O 3 -doped sample is due to the enhanced scattering of phonons , which is derives from the point defects caused by Ga-doping and the introduction of the second phase. As a result, the In 2 O 3 (ZnO) 3 +0.5 mol% Ga 2 O 3 sample achieved the highest ZT value of 0.23 at 973 K.